George, now, to the potentially lethal carbon monoxide leak at a atlanta elementary school. Firefighters discovered the unsafe conditions. And now, parents are asking, why the school reportedly had no carbon monoxide detectors located inside. Steve o ssunsami has the story. Reporter: It was a shocking scene, played out on live television. I saw kids passing out. Shivering. Reporter: Dozens of children at this atlanta grade school monday, falling out from high levels of carbon monoxide poisoning. Headache, and nausea. Reporter: Firefighters were carrying sick chil there's kids laying on the floor. At least three. And the teacher are saying, this town needs help. Reporter:500 children were forced to leave the building. At least 43 sent to hospitals. Angry parents swarmed the school, desperate to find their kids. You transported them without our permission. And you won't give them to us? Reporter: Luckily, no one was seriously hurt. And investigators traced the problem to a leaky valve on the school's furnace. This morning, that has parents asking, why aren't there carbon monoxide detectors in school buildings? If you have to have them in the home, they should have them in the schools. Reporter: Maryland and connecticut are the only two states that require core ban monoxide detectors in schools. And maryland only requires them in new schools. In texas, they have to be installed in certain day-care centers. And only 25 states require them in residential buildings. The boiler at the atlanta grade school was last checked a year ago, which isn't making parents feel any er. For "good morning america," steve osunsami, abc news, atlanta. This is leading to a move lots of schools are examining the question of whether they need to be installing these. Switch gears now. Play some music right here. ♪ You're a mean one,

This transcript has been automatically generated and may not be 100% accurate.

Carbon Monoxide Poisons Atlanta Students

At least 42 students and seven adults at Finch Elementary School were sent to hospitals.

Carbon Monoxide Suspected in Teen Deaths

A parked car's engine was running near Florida motel room where five teens died.

{"id":17873792,"title":"Carbon Monoxide Leak Sickens School Children, Teachers","duration":"2:01","description":"More than 50 students and teachers in Atlanta were sent to the hospital.","section":"GMA","mediaType":"Default"}